10 Milk and Its Products. 



they can be reabsorbed, and portions of partially 

 broken down cells break away from tlie walls of 

 the follicle and appear in the colostrum. Gradually 

 the colostrum takes on the character of normal 

 milk, and in the course of four or five days the 

 change is complete. Other characteristics of colos- 

 trum are discussed in detail in the next chapter. 



While maternity is the prime cause of secretion, 

 it is not the only means of stimulation to the ac- 

 tivity of the udder, nor is it a necessary prerequisite 

 to the secretion of milk. The regular removal 

 of the saline fluid in the gland of the virgin 

 animal, or even the stimulation of the organ by the 

 friction of the hand or the suckling of a calf, may 

 be sufftcient to cause the secretion of milk of nor- 

 mal character in considerable quantities. In the 

 same way and under the same exciting causes, other 

 glands of the body, notably the l^^llphatics in the 

 arm pits and the rudimentary mamma) of males, 

 have been known to secrete a fluid resembling milk 

 in all essential characteristics. 



Amount and duration of flou\ — With wild ani- 

 mals in a state of nature, the milk is secreted only 

 in amount sufficient for the needs of the young 

 animal, and only until the young is sufficiently de- 

 veloped to secure its food independently of the 

 mother. Under the influence of domestication the 

 cow has been brought to increase her flow of milk 

 many fold, and the time during which it is se- 

 creted has been lengthened until it is almost, and 

 indeed is, in some cases quite continuous. A dis- 



